body {
  margin: 0;
  padding: 0;
  background: #262626;
}

ul {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  margin: 0;
  padding: 0;
  display: flex;
}

ul li {
  list-style: none;
  color: #484848;
  font-family: arial;
  font-size: 5em;
  letter-spacing: 15px;
  text-shadow: none;
  animation: animate 1s infinite linear;
}

@keyframes animate {
  0% {
    color: #484848;
    text-shadow: none;
  }
  18% {
    color: #484848;
    text-shadow: none;
  }
  20% {
    color: #fff900;
    text-shadow: 0 0 7px #fff900,
                 0 0 50px #ff6c00;
  }
  30% {
    color: #484848;
    text-shadow: none;
  }
  35% {
    color: #fff900;
    text-shadow: 0 0 7px #fff900,
                 0 0 50px #ff6c00;
  }
  70% {
    color: #484848;
    text-shadow: none;
  }
  85% {
    color: #fff900;
    text-shadow: 0 0 7px #fff900,
                 0 0 50px #ff6c00;
  }
  90% {
    color: #484848;
    text-shadow: none;
  }
  100% {
    color: #484848;
    text-shadow: none;
  }
}

ul li:nth-child(1){
  animation-delay: .2s;
}

ul li:nth-child(2){
  animation-delay: .4s;
}

ul li:nth-child(3){
  animation-delay: .6s;
}

ul li:nth-child(4){
  animation-delay: .8s;
}

ul li:nth-child(5){
  animation-delay: 1s;
}

ul li:nth-child(6){
  animation-delay: 1.2s;
}

ul li:nth-child(7){
  animation-delay: 1.4s;
}